The long term objective of this project is to develop biochemically differentiated clonal cell lines of nervous system origin growing both in tissue culture and as transplantable clonal tumors. Both chemically induced rat nervous system tumors and spontaneously appearing human malignancies will be assayed for biochemical functions unique to the nervous system. Those exhibiting such functions will be introduced into tissue culture, cloned, and studied further. The principle advantages of such systems include permanence, cell type purity, availability, easy exchange among investigators, and the ability to carry out controlled cell type mixing experiment for the study of nervous system cell interaction in vitro. In addition, differentiated clonal tumors will provide a valuable tool for the study of nervous system malignancies, whereby the nervous system specific function can provide an additional parameter of study. In this application we have concentrated on means of isolating and studying oligodendroglia and Schwann cells, cells that produce myelin. These lines are expected to be useful model in vitro systems for the study of both normal myelination, and demyelinatory diseases such as multiple sclerosis and idiopathic neuritis.